CN116087584A - Probe with automatic calibration circuit, automatic calibration method and oscilloscope - Google Patents

Abstract

The application relates to the technical field of oscilloscope signal processing, and discloses a probe with an automatic calibration circuit, an automatic calibration method and an oscilloscope, wherein the circuit comprises: the probe circuit is used for receiving a detected signal and is connected with the variable capacitance circuit and the host module; the variable capacitance circuit is used for adjusting the internal capacitance according to the adjustment parameters output by the host module and is connected with the host module and the current-limiting protection circuit, wherein the adjustment parameters are positive voltage and negative voltage; the current-limiting protection circuit is used for current-limiting protection of the internal capacitor. The method and the device improve the accuracy of the input signal of the oscilloscope.

Description

Probe with automatic calibration circuit, automatic calibration method and oscilloscope

Technical Field

The present invention relates to the field of oscilloscope signal processing technology, and in particular, to a probe with an automatic calibration circuit, an automatic calibration method, and an oscilloscope.

Background

Along with the high-speed development of oscilloscope technology, oscilloscopes are used more and more frequently in various fields, and meanwhile, the accuracy and the processing cost of signal processing of the oscilloscopes are also more and more important.

Especially, after the oscilloscope is connected with the probe, the signal problem can be misjudged by a user due to poor matching between the probe and the oscilloscope. In a traditional mode, when a user connects an oscilloscope probe, the probe is connected to the square wave signal, and the user adjusts an adjustable capacitor on the probe by using an adjusting tool such as a screwdriver to calibrate the probe so as to enable the probe to be matched with the oscilloscope.

On the one hand, the user is inconvenient to adjust, and the habit of each person is different, so that the calibrated waveform is bad; on the other hand, the manufacturing process of the mechanically adjustable capacitor has large difference, and can not meet the calibration requirement of the probe in some cases.

Disclosure of Invention

The invention mainly aims to provide a probe with an automatic calibration circuit, an automatic calibration method and an oscilloscope, and aims to solve the technical problem of how to improve the accuracy of input signals of the oscilloscope.

In order to achieve the above object, the present invention provides a probe with an automatic calibration circuit, which includes a probe circuit, a connector circuit and a host module, wherein the connector circuit includes a variable capacitance circuit and a current limiting protection circuit;

the probe circuit is used for receiving the detected signal and is connected with the variable capacitance circuit and the host module;

the variable capacitance circuit is used for adjusting the internal capacitance according to the adjustment parameters output by the host module and is connected with the host module and the current-limiting protection circuit, wherein the adjustment parameters are positive voltage and negative voltage;

the current-limiting protection circuit is used for current-limiting protection of the internal capacitor.

Optionally, the varactor circuit includes a fourth resistor and a varactor group, where the varactor group includes a first varactor group and a second varactor group, one end of the fourth resistor is connected to the probe circuit and the probe end of the host module, and the other end of the fourth resistor is connected to the negative electrode of the first varactor group and the positive electrode of the second varactor group;

the positive pole of first varactor group is in proper order with current-limiting protection circuit with the negative voltage end of host computer module, the negative pole of second varactor group is in proper order with current-limiting protection circuit with the positive voltage end of host computer module.

Optionally, the varactor group is a circuit formed by one or more varactors connected in series in the same direction, the positive electrode of the varactor group after being connected in series in the same direction is the positive electrode of the varactor group, the negative electrode of the varactor group after being connected in series in the same direction is the negative electrode of the varactor group, and the varactor is used for making the varactor form reverse bias according to the adjustment parameters, fixing the internal capacitance of the varactor according to the reverse bias, and counteracting the capacitance change caused by the measured signal change through the internal capacitance.

Optionally, the current limiting protection circuit includes a fifth resistor and a sixth resistor, one end of the fifth resistor is connected with the positive electrode of the first varactor group, one end of the sixth resistor is connected with the negative electrode of the second varactor group, and the other end of the fifth resistor is grounded after being connected with the other end of the sixth resistor.

Optionally, the current-limiting protection circuit includes a second capacitor and a third capacitor, one end of the second capacitor is connected with the positive electrode of the first varactor group, one end of the third capacitor is connected with the negative electrode of the second varactor group, and the other end of the second capacitor is grounded after being connected with the other end of the third capacitor.

Optionally, the probe circuit includes a first capacitor, a probe contact, a first resistor and a second resistor, where a first end of the first resistor and a first end of the second resistor are connected in parallel and then connected to the probe contact, a second end of the first resistor is connected to the first end of the first capacitor, and a connection point between the second end of the first capacitor and the second end of the second resistor after being connected in parallel is connected to the joint circuit.

Optionally, the probe circuit includes a third resistor, one end of the third resistor is connected with the connection point, the other end of the third resistor is respectively connected with the host module and the varactor circuit, and the third resistor is used for adjusting circuit parameters in the circuit and controlling the amplitude of the measured signal to be consistent through the circuit parameters.

In addition, the application also provides an automatic calibration method, which comprises the probe with the automatic calibration circuit, and the automatic calibration method comprises the following steps:

acquiring an acquired signal;

detecting whether the signal is matched with a preset standard;

if the signal is not matched with the preset standard, determining the state of the signal;

the positive voltage and the negative voltage of the host module are regulated according to the state, the capacitance of a first varactor group and the capacitance of a second varactor group in the varactor circuit are changed according to the change of the positive voltage and the negative voltage output by the host module, and the changed calibration capacitance is obtained;

and executing the step of acquiring the acquired signals until the signals are matched with preset standards, and storing the parameters capable of outputting the positive voltage and the parameters capable of outputting the negative voltage.

Optionally, the signal is a square wave signal.

In addition, in order to achieve the above object, the present invention also provides an oscilloscope, on which an automatic calibration program is stored, which when executed by a processor, implements the steps of the automatic calibration method described above.

The application provides a probe with an automatic calibration circuit, which comprises a probe circuit, a connector circuit and a host module, wherein the connector circuit comprises a variable capacitance circuit and a current-limiting protection circuit; the variable capacitance circuit is used for adjusting the internal capacitance according to the adjustment parameters output by the host module and is connected with the host module and the current-limiting protection circuit, wherein the adjustment parameters are positive voltage and negative voltage; the current-limiting protection circuit is used for current-limiting protection of the internal capacitor. Signal fluctuation in the measured signal is counteracted by the variable capacitance circuit in the connector circuit, the size of the internal capacitor can be adjusted by the adjusting parameter in the host module, and the internal capacitor is protected by the current-limiting protection circuit, so that the phenomenon that the oscilloscope cannot calibrate the measured signal in the prior art is avoided, and the signal fluctuation in the measured signal is counteracted by the variable capacitance circuit in the connector circuit, so that the accuracy of the input signal of the oscilloscope can be ensured.

Drawings

FIG. 1 is a schematic diagram of a probe with an automatic calibration circuit according to the present invention;

FIG. 2 is a schematic diagram of the circuit connections of a probe with an auto-calibration circuit according to the present invention;

FIG. 3 is a schematic diagram of an automatic calibration device according to the present invention;

fig. 4 is a flow chart of an automatic calibration method according to the present invention.

Reference numerals illustrate:

reference numerals	Name of the name	Reference numerals	Name of the name
				10	Probe circuit	20	Joint circuit
30	Host module	S1	Probe end
				S2	Positive voltage terminal	S3	Negative voltage terminal
J1	Probe contact	R1	First resistor
				R2	Second resistor	R3	Third resistor
R4	Fourth resistor	R5	Fifth resistor
				R6	Sixth resistor	C1	First capacitor
C2	Second capacitor	C3	Third capacitor
				D1	First varactor group	D2	Second varactor group
SBQ	Oscilloscope
			21	Variable capacitance circuit
22	Protection circuit				DL	Probe with automatic calibration circuit
		ZZ	Automatic calibration device	00			Power interface module

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and rear … …) are included in the embodiments of the present invention, the directional indications are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are correspondingly changed.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.

The invention provides a probe with an automatic calibration circuit, referring to the structural schematic diagram of the probe with the automatic calibration circuit of fig. 1, the probe DL with the automatic calibration circuit comprises a probe rod circuit 10, a joint circuit 20 and a host module 30, wherein the joint circuit 20 comprises a variable capacitance circuit 21 and a current-limiting protection circuit 22;

the probe circuit 10 is configured to receive a signal to be tested and is connected to the varactor circuit 21 and the host module 30;

the varactor circuit 21 is configured to adjust an internal capacitance according to an adjustment parameter output by the host module 30, and is connected to the host module 30 and the current-limiting protection circuit 22, where the adjustment parameter is a positive voltage and a negative voltage;

the current-limiting protection circuit 22 is configured to perform current-limiting protection on the internal capacitor.

In this embodiment, the probe circuit 10 is connected with the connector circuit 20 and the host module 30, so that the whole circuit can receive an external detected signal through the probe circuit 10, when the external detected signal passes through the probe circuit 10, the fluctuation of the detected signal is processed through the internal variable capacitance circuit 21, meanwhile, in order to ensure the use safety of the internal components of the variable capacitance circuit 21, the components in the variable capacitance circuit 21 are divided by the current limiting protection circuit 22, so that the safety of the components can be protected, and the influence of the parameter value of the voltage dividing device in the current limiting protection circuit 22 on the whole circuit is not great, wherein the detected signal refers to an input signal of the oscilloscope connected with the outside, and the signal fluctuation refers to the phenomenon of signal waveform fluctuation caused by external factors. The whole circuit is improved without using more components and parts, and the whole circuit is simple to connect, so that the whole circuit is simple to realize, and the signal fluctuation in the input signal is processed while the realization cost is low, so that the accuracy of the input signal can be ensured.

Further, in still another embodiment of the probe with an automatic calibration circuit of the present application, referring to fig. 2, fig. 2 is a schematic circuit connection diagram of the probe with an automatic calibration circuit, the varactor circuit 21 includes a fourth resistor R4 and a varactor group, the varactor group includes a first varactor group D1 and a second varactor group D2, one end of the fourth resistor R4 is connected to the probe circuit 10 and the probe end S1 of the host module 30, and the other end of the fourth resistor R4 is connected to the negative electrode of the first varactor group D1 and the positive electrode of the second varactor group D2;

the positive pole of the varactor group D1 is sequentially connected to the current-limiting protection circuit 22 and the negative voltage terminal S3 of the host module 30, and the negative pole of the second varactor group D2 is sequentially connected to the current-limiting protection circuit 22 and the positive voltage terminal S2 of the host module 30.

Specifically, the varactor group is a circuit formed by one or more varactors connected in series in the same direction, the positive electrode of the varactor group after being connected in series in the same direction is the positive electrode of the varactor group, the negative electrode of the varactor group after being connected in series in the same direction is the negative electrode of the varactor group, and the varactor is used for enabling the varactor to form reverse bias according to the adjustment parameters, fixing the internal capacitance of the varactor according to the reverse bias, and counteracting capacitance change caused by the measured signal change through the internal capacitance.

Specifically, the current limiting protection circuit 22 includes a fifth resistor R5 and a sixth resistor R6, one end of the fifth resistor R5 is connected to the positive electrode of the first varactor group D1, one end of the sixth resistor R6 is connected to the negative electrode of the second varactor group D2, and the other end of the fifth resistor R5 is connected to the other end of the sixth resistor R6 and then grounded.

Specifically, the current limiting protection circuit 22 includes a second capacitor C2 and a third capacitor C3, one end of the second capacitor C2 is connected to the positive electrode of the first varactor group D1, one end of the third capacitor C3 is connected to the negative electrode of the second varactor group D2, and the other end of the second capacitor C2 is grounded after being connected to the other end of the third capacitor C3.

Specifically, the probe circuit 10 includes a first capacitor C1, a probe junction J1, a first resistor R1, and a second resistor R2, where a first end of the first resistor R1 and a first end of the second resistor R2 are connected in parallel and then connected to the probe junction J1, a second end of the first resistor R1 is connected to the first end of the first capacitor C1, and a connection point between the second end of the first capacitor C1 and the second end of the second resistor R2 after being connected in parallel is connected to the joint circuit 20.

Specifically, the probe circuit 10 includes a third resistor R3, one end of the third resistor R3 is connected to the connection point, the other end of the third resistor R3 is connected to the host module 30 and the varactor circuit 21, and the third resistor R3 is configured to adjust circuit parameters in the circuit and control the amplitude of the measured signal according to the circuit parameters.

Specifically, the host module 30 is an oscilloscope SBQ.

In the present embodiment, the varactor circuit 21 in the probe DL having the auto-calibration circuit is provided with two varactor groups (a first varactor group D1 and a second varactor group D2,) which are reversely arranged, by which external signal fluctuations can be canceled; however, due to the characteristics of the two varactors (the withstand voltage of the varactors is only tens of volts), the varactors in the varactor circuit 21 are divided by the fifth resistor R5, the sixth resistor R6, the second capacitor C2 and the third capacitor C3 in the current-limiting protection circuit 22, so as to protect the varactors in the varactor circuit 21. The fifth resistor R5 and the sixth resistor R6 are two 1M resistors, when the input end is connected with a large voltage, the voltage can be divided to protect the varactor, normal use is not affected when an oscilloscope outputs a reference signal for calibration (the load of the 1M resistor can be ignored for the oscilloscope), the resistance value of the first resistor R1 and the second resistor R2 is 9M, the resistance value of the third resistor R3 and the fourth resistor R4 is 100deg.C, the resistance value of the fifth resistor R5 and the sixth resistor R6 is 1M, the model of the remaining first capacitor C1, second capacitor C2 and third capacitor C3 is 104, and the model of the capacitor 104 is 0.1uf according to the actual capacitor model; finally, the whole circuit has simple structure, fewer used components and low cost, and because the whole circuit needs to use resistors, capacitors and varactors, the cost of the used components of the whole circuit on the manufacturing cost is low, and the effects of counteracting the waveform fluctuation of the input signal and protecting the components of the circuit can be realized.

In addition, the application also provides an automatic calibration device ZZ, which comprises the probe DL with the automatic calibration circuit.

Further, in an embodiment of the apparatus of the present application, referring to fig. 3, fig. 3 is a schematic diagram of an automatic calibration apparatus, where the automatic calibration apparatus ZZ includes a power interface module 00, and the power interface module 00 is connected to the oscillometric module 40.

In this embodiment, the probe DL with an automatic calibration circuit is disposed in the automatic calibration device ZZ, and the automatic calibration device ZZ is further provided with a power interface module 00, and the power interface module 00 supplies power to the oscilloscope in the oscillography module 40, so as to ensure that the oscilloscope works normally.

Further, in an embodiment of the apparatus of the present application, referring to fig. 4, fig. 4 is a schematic flow chart of a technical solution of an automatic calibration method, where the automatic calibration method includes the steps of:

step S10, acquiring an acquired signal;

step S20, detecting whether the signal is matched with a preset standard;

step S30, if the signal is not matched with a preset standard, determining the state of the signal;

in this embodiment, the signal may be a square wave signal or other signal, and the probe with the auto calibration circuit is connected to the host module before the square wave signal is collected, and the square wave signal is collected by the host module after the square wave signal is received. The host module may be an oscilloscope SBQ, where the host module may obtain a collected square wave signal, and detect whether the square wave signal is matched with a preset standard, that is, when the oscilloscope enters an adjustment mode, the host module will determine whether the collected square wave signal is matched with the preset standard, where the square wave signal is a signal with positive and negative levels and a standard pulse width, and the standard is a standard square wave signal to be displayed or other customized standards. When the two varactors are matched, the first varactor group and the second varactor group are not regulated, and meanwhile, the capacitance sum between the two varactors is stored to be a capacitance fixed value. Otherwise, when the two are not matched, the first varactor group and the second varactor group are adjusted, the state of the square wave signal is determined, the corresponding input voltage of the probe is adjusted, and the traditional adjusting mode is to manually adjust the mechanical variable capacitor on the probe, so as to observe whether the square wave signal meets the requirement. The corresponding probe input voltage is determined, the corresponding relation between a square wave signal and the probe input voltage is defined in advance, the probe input voltage refers to the input voltage corresponding to the positive voltage end S2 and the negative voltage end S3 of the oscilloscope, for example, square wave information is 5V, the square wave signal can be adjusted to be matched with a standard square wave signal when the corresponding probe input voltage is 1.5V, and therefore the intelligent of adjustment is improved and the accuracy of adjustment is guaranteed through the automatic adjustment of the scheme.

Step S40, positive voltage and negative voltage of the host module are regulated according to the state, and the capacitance of the first varactor group and the capacitance of the second varactor group in the varactor circuit are changed according to the change of the positive voltage and the negative voltage output by the host module, so that the changed calibration capacitance is obtained;

and step S50, executing the step of acquiring the acquired signals until the signals are matched with preset standards, and storing the parameters capable of outputting the positive voltage and the parameters capable of outputting the negative voltage.

In this embodiment, the positive voltage and the negative voltage of the host module are adjusted by the state, that is, the voltages of the positive voltage terminal S2 and the negative voltage terminal S3 of the oscilloscope cause the reverse bias of the varactor, so as to generate the capacitance, and the voltages of S2 and S3 are different, so that the capacitance values of the reverse bias voltages are different, and the form of the square wave is changed. The step of acquiring the collected square wave signal is performed until the square wave signal is matched with a preset standard signal to complete the whole adjustment process. Finally, after the adjustment, the working mode is entered, and signal fluctuation in the input signal can be counteracted through the calibration capacitance of the first varactor group and the second varactor group, so that the input signal can be automatically calibrated, and the accuracy of the input signal can be further ensured. The step of automatically calibrating the input signal by the first varactor group and the second varactor group by canceling signal fluctuation in the measured signal according to the calibration capacitance comprises the following steps:

step C31, determining a voltage value corresponding to the detected signal, and detecting whether the voltage value changes;

step C32, if the voltage value changes, determining a first capacitance value corresponding to the first varactor group, and detecting whether the first capacitance value increases;

in this embodiment, the oscilloscope may acquire, in real time, a voltage value corresponding to the measured signal in the working mode, and detect whether the voltage value changes in transmission, and when the voltage value does not change, perform real-time monitoring, where the voltage value refers to input of a corresponding voltage value. When the voltage value changes, it will detect whether the first capacitance value corresponding to the first varactor group changes, mainly detect whether the first capacitance value is affected by the voltage value to become larger or smaller, or detect whether the second capacitance value corresponding to the second varactor group changes, or detect whether the two capacitance values become larger or smaller at the same time.

And step C33, if the first capacitance value is increased, adjusting a second capacitance value corresponding to the second varactor group, so that the sum of the first capacitance value and the second capacitance value is a preset value.

In this embodiment, when the first capacitance value increases, the second capacitance value corresponding to the second varactor group is adjusted according to the situation that the first capacitance value increases, where the adjustment mode mainly includes determining the first capacitance value, extracting the most recently stored capacitance constant value, subtracting the first capacitance value from the capacitance constant value to obtain a subtraction value, and automatically adjusting the second capacitance value corresponding to the second varactor group to be equal to the subtraction value. That is, in the following working process after the adjustment mode of the varactors is determined, no matter how the input signal changes, the capacitance and dynamic balance of the two varactors can be achieved, and here, four or six equal-double-number varactors can be used for achieving dynamic balance, so that the accuracy of signal calibration can be ensured, and the accuracy of calibration cannot be affected due to the change of the input signal.

The invention also provides an oscilloscope.

The oscilloscope of the invention has stored thereon an auto-calibration program, which may be a host module in a probe with auto-calibration circuitry, which when executed by a processor implements the steps of the auto-calibration method described above.

The foregoing description is only of the optional embodiments of the present invention, and is not intended to limit the scope of the invention, and all the equivalent structural changes made by the description of the present invention and the accompanying drawings or the direct/indirect application in other related technical fields are included in the scope of the invention.

Claims (10)

1. The probe with the automatic calibration circuit is characterized by comprising a probe rod circuit, a joint circuit and a host module, wherein the joint circuit comprises a variable capacitance circuit and a current limiting protection circuit;

the probe circuit is used for receiving the detected signal and is connected with the variable capacitance circuit and the host module;

the variable capacitance circuit is used for adjusting the internal capacitance according to the adjustment parameters output by the host module and is connected with the host module and the current-limiting protection circuit, wherein the adjustment parameters are positive voltage and negative voltage;

the current-limiting protection circuit is used for current-limiting protection of the internal capacitor.

2. The probe with an automatic calibration circuit according to claim 1, wherein the varactor circuit comprises a fourth resistor and a varactor group, the varactor group comprises a first varactor group and a second varactor group, one end of the fourth resistor is respectively connected with the probe circuit and the probe end of the host module, and the other end of the fourth resistor is respectively connected with the cathode of the first varactor group and the anode of the second varactor group;

the positive pole of first varactor group is in proper order with current-limiting protection circuit with the negative voltage end of host computer module, the negative pole of second varactor group is in proper order with current-limiting protection circuit with the positive voltage end of host computer module.

3. The probe with the automatic calibration circuit according to claim 2, wherein the varactor group is a circuit formed by one or more varactors connected in series in the same direction, the positive electrode of the varactor group after being connected in series in the same direction is the positive electrode of the varactor group, the negative electrode of the varactor group after being connected in series in the same direction is the negative electrode of the varactor group, the varactor is used for making the varactor form reverse bias according to the adjustment parameter, fixing the internal capacitance of the varactor according to the reverse bias, and counteracting the capacitance change caused by the measured signal change through the internal capacitance.

4. The probe with an automatic calibration circuit according to claim 3, wherein the current limiting protection circuit comprises a fifth resistor and a sixth resistor, one end of the fifth resistor is connected with the positive electrode of the first varactor group, one end of the sixth resistor is connected with the negative electrode of the second varactor group, and the other end of the fifth resistor is grounded after being connected with the other end of the sixth resistor.

5. The probe with an automatic calibration circuit according to claim 4, wherein the current limiting protection circuit comprises a second capacitor and a third capacitor, one end of the second capacitor is connected with the positive electrode of the first varactor group, one end of the third capacitor is connected with the negative electrode of the second varactor group, and the other end of the second capacitor is grounded after being connected with the other end of the third capacitor.

6. The probe with an automatic calibration circuit of claim 5, wherein the probe circuit comprises a first capacitor, a probe contact, a first resistor, and a second resistor, the first end of the first resistor and the first end of the second resistor being connected in parallel and then connected to the probe contact, the second end of the first resistor being connected to the first end of the first capacitor, and a connection point between the second end of the first capacitor and the second end of the second resistor being connected in parallel and then connected to the connector circuit.

7. The probe with an automatic calibration circuit according to claim 6, wherein the probe circuit comprises a third resistor, one end of the third resistor is connected with the connection point, the other end of the third resistor is respectively connected with the host module and the variable capacitance circuit, and the third resistor is used for adjusting circuit parameters in the circuit and controlling the amplitude of the detected signal to be consistent through the circuit parameters.

8. An automatic calibration method, characterized in that the automatic calibration method is applied to the probe with an automatic calibration circuit according to any one of claims 1 to 7, the steps of the automatic calibration method comprising:

acquiring an acquired signal;

detecting whether the signal is matched with a preset standard;

if the signal is not matched with the preset standard, determining the state of the signal;

the positive voltage and the negative voltage of the host module are regulated according to the state, the capacitance of a first varactor group and the capacitance of a second varactor group in the varactor circuit are changed according to the change of the positive voltage and the negative voltage output by the host module, and the changed calibration capacitance is obtained;

and executing the step of acquiring the acquired signals until the signals are matched with preset standards, and storing the parameters capable of outputting the positive voltage and the parameters capable of outputting the negative voltage.

9. The method of automatic calibration according to claim 8, wherein the signal is a square wave signal.

10. An oscilloscope, characterized in that it has stored thereon an automatic calibration program which, when executed by a processor, implements the steps of the automatic calibration method as claimed in claims 8-9.

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